An imaging lens SL installed into such as an electronic still camera 1 includes, in order from an object side: a first lens group G1 having positive refractive power; a second lens group G2 having negative refractive power; a third lens group G3 having positive refractive power; and a fourth lens group G4 having positive refractive power; the second lens group G2 and the third lens group G3 move along an optical axis upon focusing from infinity to a close object, and a given conditional expression is satisfied, thereby providing a fast imaging lens capable of taking a picture from infinity to a close object with high optical performance, an optical apparatus equipped with the imaging lens, and a method for manufacturing the imaging lens.

1. An imaging lens comprising, in order from an object side: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and a fourth lens group having negative refractive power; the second lens group and the third lens group moving along an optical axis upon focusing from infinity to a close object, and the following conditional expression being satisfied: 1.20<((−β)/FNO)×(f/(−f2))<3.00 where β (negative) denotes an available shooting magnification whose absolute value gives the maximum. value, f denotes a focal length of the imaging lens, FNO denotes an f-number, and f2 denotes a focal length of the second lens group.

2. The imaging lens according to claim 1, wherein the first lens group includes an object side positive lens disposed to the most object side, and the following conditional expressions being satisfied: 1.565<nd145.0<νd1 where nd1 denotes a refractive index of the object side positive lens at d-line (wavelength λ=587.6 nm), and νd1 denotes an Abbe number of the object side positive lens at d-line.

3. The imaging lens according to claim 2, wherein the first lens group includes at least one image side positive lens having positive refractive power disposed to an image side of the object side positive lens, and the following conditional expression is satisfied: 79.0<νd2 where νd2 denotes an Abbe number of each of the image side positive lens.

4. The imaging lens according to claim 3, wherein the first lens group has at least one lens that is disposed second or later in order from the object side and is the image side positive lens.

5. The imaging lens according to claim 3, wherein the second lens counted in order from the object side of the first lens group is the image side positive lens.

6. The imaging lens according to claim 4, wherein the first lens group includes two image side positive lenses.

7. The imaging lens according to claim 1, wherein the first lens group includes at least one cemented lens.

8. The imaging lens according to claim 7, wherein the cemented lens includes a positive lens and a negative lens.

9. The imaging lens according to claim 1, wherein the first lens group includes, in order from the object side, a first lens having positive refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a sixth lens group having positive refractive power.

10. The imaging lens according to claim 9, wherein the following conditional expression is satisfied: 0.15<fGF/fGR<2.00 where fGF denotes a focal length of a front lens group, and fGR denotes a focal length of a rear lens group, in which the front lens group includes the first lens, the second lens, and the third lens in the first lens group, and the rear lens group includes the fourth lens, the fifth lens, and sixth lens in the first lens group.

11. An optical apparatus including the imaging lens according to claim 1.

12. A method for manufacturing an imaging lens including, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having negative refractive power, the method comprising steps of: disposing the second lens group and the third lens group movable along an optical axis upon focusing from infinity to a close object; and disposing each lens group with satisfying the following conditional expression: 1.20<((−β)/FNO)×(f/(−f2))<3.00 where β (negative) denotes an available shooting magnification whose absolute value gives the maximum value, f denotes a focal length of the imaging lens, FNO denotes an f-number, and f2 denotes a focal length of the second lens group.

13. The method according to claim 12, further comprising a step of: disposing an object side positive lens having positive refractive power to the most object side in the first lens group with satisfying the following conditional expressions: 1.565<nd145.0<νd1 where nd1 denotes a refractive index of the object side positive lens at d-line (wavelength λ=587.6 nm), and νd1 denotes an Abbe number of the object side positive lens at d-line.

14. The method according to claim 13, further comprising a step of: disposing at least one image side positive lens having positive refractive power to the image side of the object side positive lens in the first lens group with satisfying the following conditional expression: 79.0<νd2 where νd2 denotes an Abbe number of each of the image side positive lens.

15. The method according to claim 14, further comprising a step of: disposing at least one image side positive lens to the second or later in order from the object side in the first lens group.

16. The method according to claim 14, further comprising a step of: disposing the image side positive lens to the second, in order from the object side, of the first lens group.

17. The method according to claim 15, further comprising a step of: disposing two image side positive lens in the first lens group.

18. The method according to claim 12, further comprising a step of: disposing at least one cemented lens in the first lens group.

19. The method according to claim 18, further comprising a step of: disposing a positive lens and a negative lens in the cemented lens.

20. The method according to claim 12, further comprising a step of: disposing, in order from the object side, a first lens having positive refractive power, a second lens having positive refractive power, a third lens having negative refractive power, a fourth lens having positive refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power in the first lens group.

21. The method according to claim 20, further comprising a step of: satisfying the following conditional expression: 0.15<fGF/fGR<2.00 where fGF denotes a focal length of a front lens group, and fGR denotes a focal length of a rear lens group, in which the front lens group includes the first lens, the second lens, and the third lens in the first lens group, and the rear lens group includes the fourth lens, the fifth lens, and sixth lens in the first lens group.

Description:

The disclosure of the following priority application is herein incorporated by reference: Japanese Patent Application No. 2009-255596 filed on Nov. 7, 2009.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging lens, an optical apparatus equipped with the imaging lens, and a method for manufacturing the imaging lens.

2. Related Background Art

There has been proposed an imaging lens suitable for a film camera, an electronic still camera and a video camera in such as Japanese Patent Application Laid-Open No. 2001-021798.

However, further high optical performance has been required to the conventional imaging lens.

SUMMARY OF THE INVENTION

The present invention is made in view of the above described desire and has an object to provide a fast imaging lens capable of taking a picture from infinity to a close object with high optical performance, an optical apparatus equipped with the imaging lens, and a method for manufacturing the imaging lens.

According to a first aspect of the present invention, there is provided an imaging lens comprising, in order from an object side: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and a fourth lens group having negative refractive power; the second lens group and the third lens group moving along an optical axis upon focusing from infinity to a close object, and the following conditional expression (1) being satisfied:

1.20<((−β)/FNO)×(f/(−f2))<3.00 (1)

where β (negative) denotes an available shooting magnification whose absolute value gives the maximum value, f denotes a focal length of the imaging lens, FNO denotes an f-number, and f2 denotes a focal length of the second lens group.

In the first aspect of the present invention, it is preferable that the first lens group includes an object side positive lens disposed to the most object side, and the following conditional expressions (2) and (3) being satisfied:

1.565<nd1 (2)

45.0<νd1 (3)

where nd1 denotes a refractive index of the object side positive lens at d-line (wavelength λ=587.6 nm), and νd1 denotes an Abbe number of the object side positive lens at d-line.

In the first aspect of the present invention, it is preferable that the first lens group includes at least one image side positive lens having positive refractive power disposed to an image side of the object side positive lens, and the following conditional expression (4) is satisfied:

79.0<νd2 (4)

where νd2 denotes an Abbe number of each of the image side positive lens.

In the first aspect of the present invention, it is preferable that the first lens group has at least one lens that is disposed second or later in order from the object side and is the image side positive lens.

In the first aspect of the present invention, it is preferable that the second lens counted in order from the object side of the first lens group is the image side positive lens.

In the first aspect of the present invention, it is preferable that the first lens group includes two image side positive lenses.

In the first aspect of the present invention, it is preferable that the first lens group includes at least one cemented lens.

In the first aspect of the present invention, it is preferable that the cemented lens includes a positive lens and a negative lens.

In the first aspect of the present invention, it is preferable that the first lens group includes, in order from the object side, a first lens having positive refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a sixth lens group having positive refractive power.

In the first aspect of the present invention, it is preferable that the following conditional expression (6) is satisfied:

0.15<fGF/fGR<2.00 (6)

where fGF denotes a focal length of a front lens group, and fGR denotes a focal length of a rear lens group, in which the front lens group includes the first lens, the second lens, and the third lens in the first lens group, and the rear lens group includes the fourth lens, the fifth lens, and sixth lens in the first lens group.

According to a second aspect of the present invention, there is provided an optical apparatus including the imaging lens according to the first aspect.

According to a third aspect of the present invention, there is provided a method for manufacturing an imaging lens including, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having negative refractive power, the method comprising steps of: disposing the second lens group and the third lens group movable along an optical axis upon focusing from infinity to a close object; and disposing each lens group with satisfying the following conditional expression (1):

1.20<((−β)/FNO)×(f/(−f2))<3.00 (1)

where β (negative) denotes an available shooting magnification whose absolute value gives the maximum value, f denotes a focal length of the imaging lens, FNO denotes an f-number, and f2 denotes a focal length of the second lens group.

In the third aspect of the present invention, a following step is preferably included:

disposing an object side positive lens having positive refractive power to the most object side in the first lens group with satisfying the following conditional expressions (2) and (3):

1.565<nd1 (2)

45.0<νd1 (3)

where nd1 denotes a refractive index of the object side positive lens at d-line (wavelength λ=587.6nm), and νd1 denotes an Abbe number of the object side positive lens at d-line.

In the third aspect of the present invention, a following step is preferably included:

disposing at least one image side positive lens having positive refractive power to the image side of the object side positive lens in the first lens group with satisfying the following conditional expression (4):

79.0<νd2 (4)

where νd2 denotes an Abbe number of each of the image side positive lens.

In the third aspect of the present invention, a following step is preferably included:

disposing at least one image side positive lens to the second or later in order from the object side in the first lens group.

In the third aspect of the present invention, a following step is preferably included:

disposing the image side positive lens to the second, in order from the object side, of the first lens group.

In the third aspect of the present invention, a following step is preferably included:

disposing two image side positive lens in the first lens group.

In the third aspect of the present invention, a following step is preferably included:

disposing at least one cemented lens in the first lens group.

In the third aspect of the present invention, a following step is preferably included:

disposing a positive lens and a negative lens in the cemented lens.

In the third aspect of the present invention, a following step is preferably included:

disposing, in order from the object side, a first lens having positive refractive power, a second lens having positive refractive power, a third lens having negative refractive power, a fourth lens having positive refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power in the first lens group.

In the third aspect of the present invention, a following step is preferably included:

satisfying the following conditional expression (6):

0.15<fGF/fGR<2.00 (6)

where fGF denotes a focal length of a front lens group, and fGR denotes a focal length of a rear lens group, in which the front lens group includes the first lens, the second lens, and the third lens in the first lens group, and the rear lens group includes the fourth lens, the fifth lens, and sixth lens in the first lens group.

With constructing an imaging lens, an optical apparatus equipped with the imaging lens, and a method for manufacturing the imaging lens according to the present invention in this manner, it becomes possible to obtain a fast imaging lens capable of taking a picture from infinity to a close object with high optical performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a lens configuration of an imaging lens focusing on infinity according to Example 1 of the present application.

FIGS. 2A, 2B and 2C are graphs showing various aberrations of the imaging lens according to Example 1, in which FIG. 2A is upon focusing on infinity, FIG. 2B is upon focusing on an intermediate shooting distance, and FIG. 2C is upon focusing on a closest shooting distance.

FIG. 3 is a sectional view showing a lens configuration of an imaging lens focusing on infinity according to Example 2 of the present application.

FIGS. 4A, 4B and 4C are graphs showing various aberrations of the imaging lens according to Example 2, in which FIG. 4A is upon focusing on infinity, FIG. 4B is upon focusing on an intermediate shooting distance, and FIG. 4C is upon focusing on a closest shooting distance.

FIG. 5 is a sectional view showing a lens configuration of an imaging lens focusing on infinity according to Example 3 of the present application.

FIGS. 6A, 6B and 6C are graphs showing various aberrations of the imaging lens according to Example 3, in which FIG. 6A is upon focusing on infinity, FIG. 6B is upon focusing on an intermediate shooting distance, and FIG. 6C is upon focusing on a closest shooting distance.

FIG. 7 is a sectional view showing a lens configuration of an imaging lens focusing on infinity according to Example 4 of the present application.

FIGS. 8A, 8B and 8C are graphs showing various aberrations of the imaging lens according to Example 4, in which FIG. 8A is upon focusing on infinity, FIG. 8B is upon focusing on an intermediate shooting distance, and FIG. 8C is upon focusing on a closest shooting distance.

FIG. 9 is a sectional view showing a lens configuration of an imaging lens focusing on infinity according to Example 5 of the present application.

FIGS. 10A, 10B and 10C are graphs showing various aberrations of the imaging lens according to Example 5, in which FIG. 10A is upon focusing on infinity, FIG. 10B is upon focusing on an intermediate shooting distance, and FIG. 10C is upon focusing on a closest shooting distance.

FIGS. 11A and 11B are diagrams showing an electronic still camera equipped with an imaging lens according to the present embodiment, in which FIG. 11A is a front view, and FIG. 11B is a rear view.

FIG. 12 is a sectional view seen along the AA′ line in FIG. 11A.

FIG. 13 is a flowchart showing a method for manufacturing an imaging lens according to the present embodiment.

DESCRIPTION OF THE MOST PREFERRED EMBODIMENT

A preferred embodiment of the present application is explained below with reference to accompanying drawings. As shown in FIG. 1, an imaging lens SL according to the present embodiment includes, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a fourth lens group G4 having negative refractive power.

Moreover, in an imaging lens SL according to the present embodiment, the second lens group G2 and the third lens group G3 are moved as focusing lens groups along an optical axis upon focusing from infinity to a close object. The focusing lens groups are suitable for auto focusing, and are suitable for being driven by a motor for auto focusing such as an ultrasonic motor.

In an imaging lens SL according to the present embodiment, the following conditional expression (1) is preferably satisfied:

1.20<((−β)FNO)×(f/(−f2))<3.00 (1)

where β (negative) denotes an available shooting magnification whose absolute value gives the maximum value, f denotes a focal length of the imaging lens, FNO denotes an f-number, and f2 denotes a focal length of the second lens group G2.

Conditional expression (1) defines an appropriate relation between a shooting magnification, a focal length of the second lens group G2, and an f-number with respect to the focal length of the imaging lens. When the value ((−β)/FNO)×(f/(−f2)) is equal to or exceeds the upper limit of conditional expression (1), refractive power of the second lens group G2 becomes strong, and refractive power of the first lens group G1 becomes weak, so that a total lens length becomes long. Moreover, since refractive power of the second lens group becomes strong, spherical aberration and curvature of field become worse, so that it is undesirable. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 2.50. In order to further secure the effect of the present embodiment, it is most preferable to set the upper limit of conditional expression (1) to 2.00. On the other hand, when the value ((−β)/FNO)×(f/(−f2)) is equal to or falls below the lower limit of conditional expression (1), refractive power of the second lens group G2 becomes weak, so that refractive power of the first lens group G1 becomes strong. As a result, variations in spherical aberration and the image plane upon focusing become large, so that it is undesirable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 1.30. In order to further secure the effect of the present embodiment, it is most preferable to set the lower limit of conditional expression (1) to 1.40.

Conditional expressions for constructing such an imaging lens SL are explained. In an imaging lens SL according to the present embodiment, an object side positive lens (L11 in FIG. 1) having positive refractive power is disposed to the most object side of the first lens group G1, and the following conditional expression (2) is satisfied:

1.565<nd1 (2)

where nd1 denotes a refractive index of the object side positive lens L11 at d-line (wavelength λ=587.6 nm).

Conditional expression (2) defines the refractive index of the object side positive lens at d-line. When the value nd1 is equal to or falls below the lower limit of conditional expression (2), variations in spherical aberration and curvature of field upon focusing become large, so that it is undesirable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 1.580. Moreover, in order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 1.600.

Moreover, in an imaging lens SL according to the present embodiment, the following conditional expression (3) is preferably satisfied:

45.0<νd1 (3)

where νd1 denotes an Abbe number of the object side positive lens at d-line.

Conditional expression (3) defines an Abbe number of the object side positive lens. When the value νd1 is equal to or falls below the lower limit of conditional expression (3), the second order aberration of the first lens group G1 becomes large, so that it is undesirable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 50.00. In order to further secure the effect of the present embodiment, it is most effective to set the lower limit of conditional expression (3) to 55.00. In order to further secure the effect of the present embodiment, it is most effective to set the lower limit of conditional expression (3) to 60.00.

In an imaging lens SL according to the present embodiment, the first lens group G1 preferably includes at least one image side positive lens (for example, L12 and L14 in FIG. 1) disposed to the image side of the object side positive lens, and the following conditional expression (4) is preferably satisfied:

79.0<νd2 (4)

where νd2 denotes an Abbe number of the image side positive lens at d-line.

Conditional expression (4) defines the Abbe number of the image side positive lens. The image side positive lens is made from an anomalous dispersion glass. Such an image side positive lens is effective when it is disposed in a position where an height of ray is high, so that it is the most effective to be disposed adjoining to the image side of the object side positive lens. When the value νd2 is equal to or falls below the lower limit of conditional expression (4), secondary dispersion generated in the first lens group G1 becomes large, and longitudinal chromatic aberration on the image plane cannot be corrected, so that it is undesirable.

In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 80.0. In order to further secure the effect of the present embodiment, it is most preferable to set the lower limit of conditional expression (4) to 81.5.

In an imaging lens SL according to the present embodiment, the first lens group G1 preferably has at least one lens (for example, L12 and L14 in FIG. 1) that is disposed second or later in order from the object side and is the image side positive lens. In this case, it is further preferable that the first lens group G1 has two image side positive lenses. Moreover, the second lens counted from the object side (L12 in FIG. 1) is preferably an images side positive lens.

In an imaging lens SL according to the present embodiment, the following conditional expression (5) is preferably satisfied:

0.40<(−β)×(−f2)×FNO/f<0.90 (5)

where β (negative) denotes an available shooting magnification whose absolute value gives the maximum value, f denotes a focal length of the imaging lens, FNO denotes an f-number, and f2 denotes an focal length of the second lens group.

Conditional expression (5) defines an appropriate relation of the shooting magnification, the focal length of the second lens group G2, and the f-number with respect to the focal length of the imaging lens. When the value (−β)×(−f2)×FNO/f is equal to or exceeds the upper limit of conditional expression (5), refractive power of the second lens group G2 becomes weak, so that refractive power of the first lens group G1 becomes strong. Accordingly, variations in spherical aberration and the image plane upon focusing become large, so that it is undesirable. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.80. In order to further secure the effect of the present embodiment, it is most preferable to set the upper limit of conditional expression (5) to 0.70.

On the other hand, when the value (−β)×(−f2)×FNO/f is equal to or falls below the lower limit of conditional expression (5), refractive power of the first lens group G1 becomes weak, so that the total lens length becomes large. Moreover, refractive power of the second lens group G2 becomes strong, and spherical aberration and curvature of field become worse, so that it is undesirable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.45. In order to further secure the effect of the present embodiment, it is most preferable to set the lower limit of conditional expression (5) to 0.50.

In an imaging lens SL according to the present embodiment, the first lens group G1 preferably includes at least one cemented lens (CL11 in FIG. 1). In this case, the cemented lens preferably has a positive lens (L16 in FIG. 1) and a negative lens (L15 in FIG. 1), thereby carrying out excellent correction of spherical aberration and achromatization.

In an imaging lens SL according to the present embodiment, the first lens group G1 preferably includes, in order from the object side, a first lens L11 having positive refractive power, a second lens L12 having positive refractive power, a third lens L13 having negative refractive power, a fourth lens L14 having positive refractive power, a fifth lens L15 having negative refractive power, and a sixth lens L16 having positive refractive power. With this lens configuration, it becomes possible to keep the f-number small with securing an optical amount.

In an imaging lens SL according to the present embodiment, when a front lens group GF is composed of the first lens L11, the second lens L12, and the third lens L13, and a rear lens group GR is composed of the fourth lens L14, the fifth lens L15, and the sixth lens L16, the following conditional expression (6) is preferably satisfied:

0.15<fGF/fGR<2.00 (6)

where fGF denotes a focal length of the front lens group GF, and fGR denotes a focal length of the rear lens group GR.

conditional expression (6) defines an appropriate focal length of the front lens group GF with respect to the focal length of the rear lens group GR. When the ratio fGF/fGR is equal to or exceeds the upper limit of conditional expression (6), refractive power of the rear lens group GR becomes strong, and variation in longitudinal chromatic aberration upon focusing becomes large, so that it is undesirable. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (6) to 1.80. In order to further secure the effect of the present embodiment, it is most preferable to set the upper limit of conditional expression (6) to 1.70.

On the other hand, when the ratio fGF/fGR is equal to or falls below the lower limit of conditional expression (6), refractive power of the front lens group GF becomes strong, and variation in spherical aberration upon focusing becomes large, so that it is undesirable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.20. In order to further secure the effect of the present embodiment, it is most preferable to set the lower limit of conditional expression (6) to 0.50.

In FIGS. 11A, 11B and 12, construction of an electronic still camera 1 (hereinafter simply shown as a camera) as an optical apparatus equipped with an imaging lens SL according to the present embodiment is shown. In the camera 1, when a power switch button (not shown) is pressed, a shutter (not shown) of an image-taking lens (imaging lens SL) is opened, light from an object (not shown) is converged by the imaging lens SL, and an image is formed on an imaging device C (such as a CCD, or CMOS) disposed on the image plane I. The object image formed on the imaging device C is displayed on a liquid crystal monitor 2 disposed backside of the camera 1. After fixing the image composition of the object image with observing the liquid crystal monitor 2, a photographer depresses a release button 3 to take a picture of the object image by the imaging device C, and stores in a memory (not shown).

In the camera 1, the following members are disposed such as an auxiliary light emitter 4 that emits auxiliary light when the object is dark, a W-T button 5 that makes the zoom lens system carry out zooming between a wide-angle end state (W) and a telephoto end state (T), and a function button 6 that is used for setting various conditions of the camera 1. Although a compact-type camera, in which an imaging lens SL and a camera are formed integrally, is shown in FIG. 11, an optical apparatus may be a single-lens reflex camera that a camera body and a lens barrel including an imaging lens SL are removable.

Then, a method for manufacturing an imaging lens SL according to the present embodiment is explained with reference to FIG. 13.

Step S100:

Each lens group is prepared with disposing each lens into each lens group. In particular, in the present embodiment, for example, in order from an object side, a double convex positive lens L11, a positive meniscus lens L12 having a convex surface facing the object side, a double concave negative lens L13, a double convex positive lens L14, and a cemented lens CL11 constructed by a negative meniscus lens L15 having a convex surface facing the object side cemented with a positive meniscus lens L16 having a convex surface facing the object side are disposed in the first lens group G1. In order from the object side, a negative meniscus lens L21 having a convex surface facing the object side, and a cemented lens CL21 constructed by a double concave negative lens L22 cemented with a positive meniscus lens L23 having a convex surface facing the object side are disposed in the second lens group G2. In order from the object side, a double convex positive lens L31, and a cemented lens CL31 constructed by a double convex positive lens L32 cemented with a negative meniscus lens L33 having a convex surface facing the image side are disposed in the third lens group G3. In order from the object side, a double concave negative lens L41, a double convex positive lens L42, and a double concave negative lens L43 are disposed in the second lens group G4. With disposing each lens group provided in this manner, an imaging lens SL is manufactured.

Step S200:

Disposing the second lens group G2 and the third lens group G3 movably along an optical axis upon focusing from infinity to a close object.

Step S300:

Disposing each lens group with satisfying the following conditional expression (1):

1.20<((−β)/FNO)×(f/(−f2))<3.00 (1)

where β (negative) denotes an available shooting magnification whose absolute value gives the maximum value, f denotes a focal length of the imaging lens, FNO denotes an f-number, and f2 denotes a focal length of the second lens group G2.

Each example of the present embodiment is explained below with reference to accompanying drawings. FIGS. 1, 3, 5, 7 and 9 are sectional views showing lens configurations of imaging lenses SL (SL1 through SL5) and movement of each lens group upon focusing from infinity to a close object. As shown in each drawing, an imaging lens SL according to each example is composed of, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a fourth lens group G4 having negative refractive power. In the first lens group G1, an object side positive lens L11 having positive refractive power is disposed to the most object side thereof, and an image side positive lens L12 having positive refractive power is disposed to the image side of the object side positive lens L11. The second lens group G2 and the third lens group G3 are moved along an optical axis upon carrying out focusing from infinity to a close object. An aperture stop S is disposed between the second lens group G2 and the third lens group G3.

EXAMPLE 1

FIG. 1 is a sectional view showing a lens configuration of an imaging lens SL1 according to Example 1 of the present application focusing on infinity. In the imaging lens SL1 shown in FIG. 1, the first lens group G1 is composed of, in order from and object side, a double convex positive lens L11, a positive meniscus lens L12 having a convex surface facing the object side, a double concave negative lens L13, a double convex positive lens L14, and a cemented lens CL11 constructed by a negative meniscus lens L15 having a convex surface facing the object side cemented with a positive meniscus lens L16 having a convex surface facing the object side. The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L21 having a convex surface facing the object side, and a cemented lens CL 21 constructed by a double concave negative lens L22 cemented with a positive meniscus lens L23 having a convex surface facing the object side. The third lens group G3 is composed of, in order from the object side, a double convex positive lens L31, and a cemented lens CL 31 constructed by a double convex positive lens L32 cemented with a negative meniscus lens L33 having a convex surface facing the image side. The fourth lens group G4 is composed of, in order from the object side, a double concave negative lens L41, a double convex positive lens L42, and a double concave negative lens L43.

Various values associated with the imaging lens SL1 according to Example 1 are listed in Table 1.

In Table 1, f denotes a focal length of the imaging lens SL1, FNO denotes an f-number, β denotes a shooting magnification, and Bf denotes a distance between an image side surface of the most image side lens and an image plane, TL denotes a total lens length. In [Lens Data], the left most column “i” shows the lens surface number counted in order from the object side, the second column “r” shows a radius of curvature of the lens surface, the third column “d” shows a distance to the next surface, the fourth column “νd” shows an Abbe number at d-line (wavelength λ=587.6 nm), and the fifth column “nd” shows refractive index at d-line (wavelength λ=587.6 nm). In the fifth column “nd” refractive index of the air nd=1.000000 is omitted. In the second column “r”, r=∞ denotes a plane surface. In [Variable Distances], β, variable distances, Bf and a total lens length TL with respect to shooting distance d0 of infinity (INF), an intermediate shooting distance (MID) (β=−0.5), and a closest shooting distance (CLD) (β=−1.0) are shown. In [Values for Conditional Expressions], values for respective conditional expressions are shown.

In respective tables for various values, “mm” is generally used for the unit of length such as the focal length, the radius of curvature and the distance to the next lens surface. However, since similar optical performance can be obtained by an optical system proportionally enlarged or reduced its dimension, the unit is not necessarily to be limited to “mm”, and any other suitable unit can be used.

The explanation of reference symbols is the same in the other Examples.

TABLE 1

[Specifications]

f = 199.96976

FNO = 2.46

[Lens Data]

i

r

d

νd

nd

1

298.1633

10.0000

58.55

1.651597

2

−284.3000

1.0000

3

86.0789

12.5000

82.52

1.497820

4

1451.5525

3.0000

5

−368.5872

3.5000

34.96

1.800999

6

228.3831

10.6267

7

159.9332

8.0000

70.41

1.487490

8

−314.4280

0.1000

9

64.8733

3.5000

41.96

1.667551

10

35.8768

12.0000

82.52

1.497820

11

144.1260

(d11)

12

435.6646

2.8000

65.44

1.603001

13

55.4486

5.0000

14

−455.1677

2.7000

69.98

1.518601

15

36.0015

5.5000

25.43

1.805181

16

52.6821

(d16)

17

∞

(d17)

Aperture Stop S

18

144.7963

5.0000

82.52

1.497820

19

−124.6815

0.5000

20

90.9873

8.0000

60.29

1.620411

21

−68.8895

1.8000

30.13

1.698947

22

−327.4296

(d22)

23

−146.1501

2.0000

23.78

1.846660

24

55.0000

2.8562

25

62.7116

8.0000

23.78

1.846660

26

−109.3188

0.1000

27

−257.3955

2.0000

69.98

1.518601

28

105.3047

57.9810

[Variable Distances]

INF

MID

CLD

β=

0

−0.5

−1.0

d0=

∞

377.60300

235.95060

d11=

4.00000

18.80254

34.77331

d16=

35.77330

20.97077

5.00000

d17=

44.74376

21.33048

5.97949

d22=

4.00000

27.41329

42.76428

Bf=

57.98100

58.24403

58.52183

TL=

249.83294

250.09597

250.37377

[Values for Conditional Expressions]

β = −1.0

FNO = 2.46

f = 199.96976

f2 = −53.900

(1)((−β)/FNO) × (f/(−f2)) = 1.51

(2)nd1 = 1.652

(3)νd1 = 58.55

(4)νd2 = 82.52

(5)(−β) × (−f2) × FNo/f = 0.663

(6)fGF/fGR = 1.452

FIGS. 2A, 2B and 2C are graphs showing various aberrations of the imaging lens according to Example 1, in which FIG. 2A is upon focusing on infinity, FIG. 2B is upon focusing on an intermediate shooting distance (β=−0.5), and FIG. 2C is upon focusing on a closest shooting distance (β=−1.0).

In respective graphs, FNO denotes an f-number, NA denotes a numerical number, Y denotes an image height, and ω denotes a half angle of view (unit: degrees). In respective graphs, D denotes an aberration curve at d-line (wavelength λ=587.6 nm), and G denotes an aberration curve at g-line (wavelength λ=435.8 nm). In graphs showing astigmatism and distortion, the maximum value of the image height Y is shown. In graphs showing coma, value of each image height is shown. In the graph showing astigmatism, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. The above-described explanations regarding various aberration graphs are the same as the other Examples.

As is apparent from FIGS. 2A, 2B and 2C, the imaging lens according to Example 1 shows superb optical performance as a result of good corrections to various aberrations over entire focusing range from infinity to a close object.

EXAMPLE 2

FIG. 3 is a sectional view showing a lens configuration of an imaging lens SL2 according to Example 2 of the present application focusing on infinity. In the imaging lens SL2 shown in FIG. 3, the first lens group G1 is composed of, in order from and object side, a double convex positive lens L11, a positive meniscus lens L12 having a convex surface facing the object side, a double concave negative lens L13, a double convex positive lens L14, and a cemented lens CL11 constructed by a negative meniscus lens L15 having a convex surface facing the object side cemented with a positive meniscus lens L16 having a convex surface facing the object side. The second lens group G2 is composed of, in order from the object side, a double concave negative lens L21, and a cemented lens CL 21 constructed by a double concave negative lens L22 cemented with a positive meniscus lens L23 having a convex surface facing the object side. The third lens group G3 is composed of, in order from the object side, a double convex positive lens L31, and a cemented lens CL 31 constructed by a double convex positive lens L32 cemented with a negative meniscus lens L33 having a convex surface facing the image side. The fourth lens group G4 is composed of, in order from the object side, a double concave negative lens L41, a double convex positive lens L42, and a double convex positive lens L43.

Various values associated with the imaging lens SL2 according to Example 2 are listed in Table 2.

TABLE 2

[Specifications]

f = 169.98735

FNO = 2.50

[Lens Data]

i

r

d

νd

nd

1

211.2162

10.5000

55.40

1.677900

2

−384.5087

0.9043

3

74.2569

14.0000

82.52

1.497820

4

1721.7830

1.8085

5

−789.7207

3.1649

35.04

1.749500

6

257.0044

11.8180

7

201.5450

5.0000

91.20

1.456000

8

−760.5152

0.1000

9

60.3722

3.1649

41.17

1.701540

10

31.6491

10.0000

82.52

1.497820

11

89.1239

(d11)

12

−649.9643

2.5319

65.44

1.603001

13

53.1965

5.0000

14

−125.0621

2.4415

62.06

1.588245

15

33.6580

4.0000

25.43

1.805181

16

55.7399

(d16)

17

∞

(d17)

Aperture Stop S

18

69.9907

7.5000

63.37

1.618000

19

−104.2598

0.4521

20

211.9953

6.5106

91.20

1.456000

21

−60.8154

1.6277

23.78

1.846660

22

−195.3139

(d22)

23

−66.8968

1.8085

35.04

1.749500

24

55.0000

2.8101

25

262.6091

3.8000

27.51

1.755199

26

−543.4102

0.0904

27

66.7147

5.5000

25.43

1.805181

28

−135.4887

43.9357

[Variable Distances]

INF

MID

CLD

β=

0

−0.5

−1.0

d0=

∞

466.79610

297.31720

d1=

4.00001

26.37250

45.56607

d16=

46.56607

24.19357

5.00000

d17=

8.20000

3.90000

3.00000

d22=

34.70030

39.00030

39.90030

Bf=

43.93570

43.73004

44.50869

TL=

241.93545

241.72979

242.50844

[Values for Conditional Expressions]

β = −1.0

FNO = 2.42

f = 169.98735

f2 = −40.801

(1)((−β)/FNO) × (f/(−f2)) = 1.72

(2)nd1 = 1.678

(3)νd1 = 55.40

(4)νd2 = 82.52

(5)(−β) × (−f2) × FNo/f = 0.580

(6)fGF/fGR = 0.221

FIGS. 4A, 4B and 4C are graphs showing various aberrations of the imaging lens according to Example 2, in which FIG. 4A is upon focusing on infinity, FIG. 4B is upon focusing on an intermediate shooting distance (β=−0.5), and FIG. 4C is upon focusing on a closest shooting distance (β=−1.0).

As is apparent from FIGS. 4A, 4B and 4C, the imaging lens according to Example 2 shows superb optical performance as a result of good corrections to various aberrations over entire focusing range from infinity to a close object.

EXAMPLE 3

FIG. 5 is a sectional view showing a lens configuration of an imaging lens SL3 according to Example 3 of the present application focusing on infinity. In the imaging lens SL3 shown in FIG. 5, the first lens group G1 is composed of, in order from and object side, a double convex positive lens L11, a positive meniscus lens L12 having a convex surface facing the object side, a double concave negative lens L13, a double convex positive lens L14, and a cemented lens CL11 constructed by a negative meniscus lens L15 having a convex surface facing the object side cemented with a positive meniscus lens L16 having a convex surface facing the object side. The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L21 having a convex surface facing the object side, and a cemented lens CL 21 constructed by a double concave negative lens L22 cemented with a positive meniscus lens L23 having a convex surface facing the object side. The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L31 having a concave surface facing the object side, and a cemented lens CL 31 constructed by a double convex positive lens L32 cemented with a negative meniscus lens L33 having a convex surface facing the image side. The fourth lens group G4 is composed of, in order from the object side, a cemented lens CL 41 constructed by a positive meniscus lens L41 having a convex surface facing the image side cemented with a double concave negative lens L42, a double convex positive lens L43, and a double concave negative lens L44.

Various values associated with the imaging lens SL3 according to Example 3 are listed in Table 3.

TABLE 3

[Specifications]

f = 198.00003

FNO = 3.21

[Lens Data]

i

r

d

νd

nd

1

129.7596

9.3000

55.52

1.696797

2

−731.2617

1.0000

3

76.9560

9.2000

82.52

1.497820

4

259.2427

4.2000

5

−301.5232

3.5000

33.89

1.803840

6

206.8971

0.1000

7

118.7575

8.5000

82.52

1.497820

8

−274.2081

0.1952

9

52.1747

3.5000

45.29

1.794997

10

31.0793

11.2000

82.52

1.497820

11

152.0694

(d11)

12

388.1555

2.5000

47.38

1.788001

13

34.2544

4.3000

14

−296.4558

2.3000

60.29

1.620410

15

26.4313

5.5000

31.59

1.756920

16

96.9634

(d16)

17

∞

(d17)

Aperture Stop S

18

−1970.5204

3.5000

82.52

1.497820

19

−78.6469

0.5000

20

50.2171

8.0000

82.52

1.497820

21

−32.7001

1.8000

33.89

1.803840

22

−56.2120

(d22)

23

−106.7266

5.0000

25.68

1.784723

24

−34.9543

1.8000

55.48

1.638540

25

35.7172

12.3237

26

45.5316

7.0000

46.57

1.804000

27

−1028.7209

0.5000

28

−1610.3480

2.0000

23.78

1.846660

29

85.1001

41.2322

[Variable Distances]

INF

MID

CLD

β=

0

−0.5

−1.0

d0=

∞

385.26190

238.37790

d11=

9.72009

19.44212

30.03625

d16=

25.44056

15.71854

5.12440

d17=

27.52794

12.21742

1.81442

d22=

3.05288

18.36340

28.76640

Bf=

41.23220

41.26834

41.23514

TL=

214.69255

214.72869

214.69549

[Values for Conditional Expressions]

β = −1.0

FNO = 3.21

f = 198.00003

f2 = −37.640

(1)((−β)/FNO) × (f/(−f2)) = 1.64

(2)nd1 = 1.697

(3)νd1 = 55.52

(4)νd2 = 82.52

(5)(−β) × (−f2) × FNo/f = 0.609

(6)fGF/fGR = 1.690

FIGS. 6A, 6B and 6C are graphs showing various aberrations of the imaging lens according to Example 3, in which FIG. 6A is upon focusing on infinity, FIG. 6B is upon focusing on an intermediate shooting distance (β=−0.5), and FIG. 6C is upon focusing on a closest shooting distance (β=−1.0).

As is apparent from FIGS. 6A, 6B and 6C, the imaging lens according to Example 3 shows superb optical performance as a result of good corrections to various aberrations over entire focusing range from infinity to a close object.

EXAMPLE 4

FIG. 7 is a sectional view showing a lens configuration of an imaging lens SL4 according to Example 4 of the present application focusing on infinity. In the imaging lens SL4 shown in FIG. 7, the first lens group G1 is composed of, in order from and object side, a double convex positive lens L11, a positive meniscus lens L12 having a convex surface facing the object side, a double concave negative lens L13, a double convex positive lens L14, and a cemented lens CL11 constructed by a negative meniscus lens L15 having a convex surface facing the object side cemented with a positive meniscus lens L16 having a convex surface facing the object side. The second lens group G2 is composed of, in order from the object side, a double concave negative lens L21, and a cemented lens CL 21 constructed by a double concave negative lens L22 cemented with a positive meniscus lens L23 having a convex surface facing the object side. The third lens group G3 is composed of, in order from the object side, a double convex positive lens L31, and a cemented lens CL 31 constructed by a double convex positive lens L32 cemented with a negative meniscus lens L33 having a convex surface facing the image side. The fourth lens group G4 is composed of, in order from the object side, a double concave negative lens L41, a double convex positive lens L42, and a double concave negative lens L43.

Various values associated with the imaging lens SL4 according to Example 4 are listed in Table 4.

TABLE 4

[Specifications]

f = 219.98771

FNO = 2.04

[Lens Data]

i

r

d

νd

nd

1

258.3171

15.0000

54.66

1.729157

2

−463.5027

0.3000

3

118.3970

16.0000

67.90

1.593190

4

911.5383

3.8000

5

−639.7392

3.8506

32.35

1.850260

6

223.5223

9.1199

7

125.4664

12.8000

91.20

1.456000

8

−684.1438

0.1594

9

92.1119

3.8506

47.38

1.788001

10

49.9130

14.5000

82.52

1.497820

11

210.9790

(d11)

12

−4316.8254

3.0805

55.52

1.696797

13

81.5657

5.6000

14

−477.8628

2.9704

55.52

1.696797

15

45.3786

7.5000

23.78

1.846660

16

85.1484

(d16)

17

∞

(d17)

Aperture Stop S

18

146.1050

6.5000

82.52

1.497820

19

−134.0472

0.3000

20

96.7435

12.0000

65.46

1.603001

21

−60.5750

1.9803

35.04

1.749500

22

−183.0858

(d22)

23

−118.1879

2.2003

30.13

1.698950

24

50.6161

10.7983

25

84.1488

11.5000

35.04

1.749500

26

−60.1396

0.1100

27

−71.7556

2.2003

70.45

1.487490

28

444.5196

58.6015

[Variable Distances]

INF

MID

CLD

β=

0

−0.5

−1.0

d0=

∞

461.83610

310.25050

d11=

8.93482

32.30173

53.30294

d16=

48.67817

25.31126

4.31005

d17=

38.99927

18.58195

3.58851

d22=

9.87060

30.28791

45.28135

Bf=

58.60150

58.51021

57.65735

TL=

311.20498

311.11369

310.26083

[Values for Conditional Expressions]

β = −1.0

FNO = 2.04

f = 219.98771

f2 = −56.841

(1)((−β)/FNO) × (f/(−f2)) = 1.90

(2)nd1 = 1.729

(3)νd1 = 54.66

(4)νd2 = 91.20

(5)(−β) × (−f2) × FNo/f = 0.527

(6)fGF/fGR = 1.152

FIGS. 8A, 8B and 8C are graphs showing various aberrations of the imaging lens according to Example 4, in which FIG. 8A is upon focusing on infinity, FIG. 8B is upon focusing on an intermediate shooting distance (β=−0.5), and FIG. 8C is upon focusing on a closest shooting distance (β=−1.0).

As is apparent from FIGS. 8A, 8B and 8C, the imaging lens according to Example 4 shows superb optical performance as a result of good corrections to various aberrations over entire focusing range from infinity to a close object.

EXAMPLE 5

FIG. 9 is a sectional view showing a lens configuration of an imaging lens SL5 according to Example 5 of the present application focusing on infinity. In the imaging lens SL5 shown in FIG. 9, the first lens group G1 is composed of, in order from and object side, a double convex positive lens L11, positive meniscus lens L12 having a convex surface facing the object side, a double concave negative lens L13, a positive meniscus lens L14 having a convex surface facing the object side, and a cemented lens CL11 constructed by a negative meniscus lens L15 having a convex surface facing the object side cemented with a positive meniscus lens L16 having a convex surface facing the object side. The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L21 having a convex surface facing the object side, and a cemented lens CL 21 constructed by a double concave negative lens L22 cemented with a positive meniscus lens L23 having a convex surface facing the object side. The third lens group G3 is composed of, in order from the object side, a double convex positive lens L31, and a cemented lens CL 31 constructed by a double convex positive lens L32 cemented with a negative meniscus lens L33 having a convex surface facing the image side. The fourth lens group G4 is composed of, in order from the object side, a double concave negative lens L41, a double convex positive lens L42, and a double concave negative lens L43.

Various values associated with the imaging lens SL5 according to Example 5 are listed in Table 5.

TABLE 5

[Specifications]

f = 160.01928

FNO = 2.87

[Lens Data]

i

r

d

νd

nd

1

189.3966

11.5000

65.47

1.603000

2

−256.5570

0.2182

3

66.3234

14.0000

91.38

1.456000

4

488.9346

2.5000

5

−800.0000

3.5000

32.35

1.850260

6

181.6514

7.0000

7

76.7085

7.0000

82.56

1.497820

8

477.4907

0.1000

9

44.6509

2.8004

47.38

1.788000

10

27.8882

11.5000

91.20

1.456000

11

140.9438

(d11)

12

177.9173

2.2404

57.34

1.670000

13

37.6470

4.5000

14

−235.9017

2.1603

55.52

1.696797

15

29.1580

4.4442

23.78

1.846660

16

58.5189

(d16)

17

∞

(d17)

Aperture Stop S

18

84.6544

4.5000

82.52

1.497820

19

−66.7276

0.2182

20

56.2011

8.0000

82.52

1.497820

21

−43.4875

1.4402

35.04

1.749500

22

−113.1902

(d22)

23

−88.9707

2.0000

32.11

1.672700

24

38.1868

5.0000

25

53.0515

10.0000

34.96

1.801000

26

−43.0712

0.5000

27

−45.8497

1.6003

65.47

1.603000

28

76.3227

37.2903

[Variable Distances]

INF

MID

CLD

β=

0

−0.5

−1.0

d0=

∞

309.71390

196.91690

d11=

1.43518

13.21354

25.04256

d16=

26.05596

14.27760

2.44858

d17=

29.17815

15.21786

5.25829

d22=

2.24602

16.20631

26.16588

Bf=

37.29034

37.42219

37.29068

TL=

202.92784

203.05973

202.92822

[Values for Conditional Expressions]

β = −1.0

FNO = 2.87

f = 160.01928

f2 = −36.317

(1)((−β)/FNO) × (f/(−f2)) = 1.54

(2)nd1 = 1.603

(3)νd1 = 65.47

(4)νd2 = 91.38

(5)(−β) × (−f2) × FNo/f = 0.651

(6)fGF/fGR = 1.301

FIGS. 10A, 10B and 10C are graphs showing various aberrations of the imaging lens according to Example 5, in which FIG. 10A is upon focusing on infinity, FIG. 10B is upon focusing on an intermediate shooting distance (β=−0.5), and FIG. 10C is upon focusing on a closest shooting distance (β=−1.0).

As is apparent from FIGS. 10A, 10B and 10C, the imaging lens according to Example 5 shows superb optical performance as a result of good corrections to various aberrations over entire focusing range from infinity to a close object.

Incidentally, the following description may suitably be applied within limits that do not deteriorate optical performance.

Although an imaging lens with a four-lens-group configuration is shown as each Example of the present application, the lens-group configuration according to the present application is not limited to this, other lens-group configurations such as a five-lens-group configuration or a six-lens-group configuration is possible. Moreover, a lens configuration that a lens or a lens group is added to the object side thereof is possible, and a lens configuration that a lens or a lens group is added to the image side thereof is also possible. Incidentally, a lens group means a portion that includes at least one lens and is separated by air spaces that vary upon focusing.

In an imaging lens according to the present application, a lens group or a portion of a lens group may be shifted in a direction including a component perpendicular to the optical axis as a vibration reduction lens group, or tilted (swayed) in a direction including the optical axis for correcting an image blur caused by a camera shake. In an imaging lens according to the present application, it is particularly preferable that at least a portion of the fourth lens group G4 is used as a vibration reduction lens group.

A lens surface of a lens composing an imaging lens according to the present application may be a spherical surface, a plane surface, or an aspherical surface. When a lens surface is a spherical surface or a plane surface, lens processing, assembling and adjustment become easy, and deterioration in optical performance caused by lens processing, assembling and adjustment errors can be prevented, so that it is preferable. Moreover, even if the surface is shifted, deterioration in optical performance is little, so that it is preferable. When a lens surface is an aspherical surface, the aspherical surface may be fabricated by a fine grinding process, a glass molding process that a glass material is formed into an aspherical shape by a mold, or a compound type process that a resin material is formed into an aspherical shape on a glass lens surface. A lens surface may be a diffractive optical surface, and a lens may be a graded-index type lens (GRIN lens) or a plastic lens.

In an imaging lens according to the present application, although an aperture stop is preferably provided between the second lens group G2 and the third lens group G3, the function may be substituted by a lens frame without disposing a member as an aperture stop.

An antireflection coating having high transmittance over a broad wavelength range may be applied to each lens surface of an imaging lens according to the present application to reduce flare or ghost images, so that high optical performance with high contrast can be attained.

In an imaging lens SL according to the present application, the first lens group G1 preferably includes three positive lens components and one negative lens component. The first lens group G1 preferably disposes these lens components, in order from the object side, positive-positive-negative-positive with an air space between each of them.

In an imaging lens SL according to the present application, the second lens group G2 preferably includes two negative lens components. In an imaging lens SL according to the present application, the third lens group G3 preferably includes two positive lens components.

In an imaging lens SL according to the present application, the fourth lens group G4 preferably includes one positive lens component and one negative lens component. The fourth lens group G4 preferably disposes these lens components, in order from the object side, negative-positive with an air space between each of them.

Above-described each example only shows a specific example for the purpose of better understanding of the present invention. Accordingly, it is needless to say that the invention in its broader aspect is not limited to the specific details and representative devices shown and described herein.